After importing the StreetMap, simply place an Empty Actor in your scene (drag one out from the Modes panel), then click “Add Component” on the right and scroll down to “Street Map”. This will add a Street Map component onto your actor. Now look for the “Street Map” property on the component, then drag and drop your newly-imported asset onto that slot. You should now see your map in the level! If you can’t find it, try double-clicking on your actor in the World Outliner to make the camera jump to the object in the scene. Hope that helps!
–Mike